Associated with the color in the sRGB space, a <color> value also consists of an alpha-channel coordinate, transparency value, indicating how the color should composite with its background color.

Though CSS color values are precisely defined, they may appear differently on an output device. Most of them are not calibrated, and some browsers do not support output devices' color profile. Without these, color rendering may vary a lot.

Note: The WCAG 2.0 recommendation from the W3C strongly advises web authors not to use color as the only mean to convey a specific information, action or result. Some users have problem to distinguish colors and the conveyed information may not be grasped. Of course, this doesn't prevent the usage of color, only its usage as the only mean to describe some information.

Interpolation

Values of the <color> CSS data type can be interpolated in order to perform animations or for creating <gradient> values. In that case they are interpolated on each of their red, green, blue components, each handled as a real, floating-point, numbers. Note that interpolation of colors happens in the alpha-premultiplied sRGBA color space to prevent unexpected grey colors to appear. In animations, the speed of the interpolation is determined by the timing function associated with the animation.

Values

There are several ways to describe a <color> value.

Color Keywords

Color keywords are case-insensitive identifiers which represent a specific color, e.g. red, blue, brown, lightseagreen. The name describes the color, though it is mostly artificial. The list of accepted values varied a lot through the different specification:

CSS Level 1 only accepted 16 basic colors, named the VGA colors as they were taken from the set of displayable colors on VGA graphic cards.

CSS Level 2 added the orange keyword.

From the beginning, browsers accepted other colors, mostly the X11 named colors list as some early browsers where X11 applications, though with a few differences. SVG 1.0 was the first standard to formally defined these keywords; CSS Colors Level 3 also formally defined these keywords. They are often referred as the extended color keywords, the X11 colors, the SVG colors.

There are a few caveats to consider when using keywords:

Except the 16 basic colors which are common with HTML, the others cannot be used in HTML. HTML will convert these unknown values with a specific algorithm which will lead to completely different colors. These keywords should only be used in SVG & CSS.

Unknown keywords make the CSS property invalid. Invalid properties being ignored, the color will have no effect. This is a different behavior than the one of HTML.

No keyword-defined colors in CSS have any transparency, they are plain, solid colors.

Several keywords denote the same colors:

darkgray /darkgrey

darkslategray /darkslategrey

dimgray /dimgrey

lightgray / lightgrey

lightslategray / lightslategrey

gray / grey

slategray /slategray

Though the names of the keywords have been taken by the usual X11 color names, the color may diverge from the corresponding system color on X11 system as these are tailored for the specific hardware by the manufacturer .

transparent Keyword

The transparent keyword represents a fully transparent color, i.e. the color seen will be the background color. Technically, it is a black with alpha channel at its maximum and is a shortcut for rgba(0,0,0,0).

Historical Note
The transparent keyword wasn't a true color in CSS Level 2 (Revision 1). It was a specific keyword that could be used in place of a regular <color> value on two CSS properties: {{ Cssxref("background") }} and {{ Cssxref("border") }}. It was essentially added to allow to override an inherited solid colors.

With the support of opacity through alpha channels, transparent was redefined as a true color in CSS Level 3 allowing its use in any place where a <color> value is required, like the {{ Cssxref("color") }} property.[**]

currentColor Keyword

The currentColor keyword represents the calculated value of the element's {{ Cssxref("color") }} property. It allows to make the color properties inherited by properties or child's element properties that do not inherit it by default.

It can also be used on properties that inherit the calculated value of the element's {{ Cssxref("color") }} property and will be equivalent to the inherit keyword on these elements, if any.

Live Example

The color of the line (a color-filled div) adapts to the color of its {{ Cssxref("color") }} property, inherited from its parent

<div style="color:darkred">
The color of this text is the same as the one of the line:
<div style="background:currentcolor; height:1px"></div>
Some more text.
</div>

The color of this text is the same as the one of the line:

.

Some more text.

<div style="color:blue">
The color of this text is the same as the one of the line:
<div style="background:currentcolor; height:1px"></div>
Some more text.
</div>

The color of this text is the same as the one of the line:

.

Some more text.

RGB (red-green-blue)

Hexadecimal notation #RRGGBB and #RGB

"#", followed by six hexadecimal characters (0-9, A-F).

"#", followed by three hexadecimal characters (0-9, A-F).

The three-digit RGB notation (#RGB) and the six-digit form (#RRGGBB) are equal.
For example, #f03 and #ff0033 represent the same color.

Functional Notation rgb(R,G,B)

"rgb", followed by three {{ Xref_cssinteger() }} or three {{ Xref_csspercentage() }} values.
The integer number 255 corresponds to 100%, and to F or FF in the hexadecimal notation.

HSL (hue-saturation-lightness) hsl(H,S,L)

The advantage of HSL over RGB is that it is far more intuitive: you can guess at the colors you want, and then tweak. It is also easier to create sets of matching colors (by keeping the hue the same and varying the lightness/darkness, and saturation).

Hue is represented as an angle of the color circle (i.e. the rainbow represented in a circle). This angle is given as a unitless {{ Xref_cssnumber() }}. By definition red=0=360, and the other colors are spread around the circle, so green=120, blue=240, etc. As an angle, it implicitly wraps around such that -120=240 and 480=120.

Saturation and lightness are represented as percentages.100% is full saturation, and 0% is a shade of grey.100% lightness is white, 0% lightness is black, and 50% lightness is "normal".

System Colors

Not all system colors are supported on all systems. {{ deprecated_inline() }} for use on public web pages.

ActiveBorder

Active window border.

ActiveCaption

Active window caption. Should be used with CaptionText foreground color.

AppWorkspace

Background color of multiple document interface.

Background

Desktop background.

ButtonFace

Face background color for 3-D elements that appear 3-D due to one layer of surrounding border. Should be used with ButtonText foreground color.

ButtonHighlight

The color of the border facing the light source for 3-D elements that appear 3-D due to one layer of surrounding border.

ButtonShadow

The color of the border away from the light source for 3-D elements that appear 3-D due to one layer of surrounding border.

ButtonText

Text on push buttons. Should be used with ButtonFace or ThreeDFace background color.

CaptionText

Text in caption, size box, and scrollbar arrow box. Should be used with ActiveCaption background color.

GrayText

Grayed (disabled) text.

Highlight

Item(s) selected in a control. Should be used with HighlightText foreground color.

HighlightText

Text of item(s) selected in a control. Should be used with Highlight background color.

InactiveBorder

Inactive window border.

InactiveCaption

Inactive window caption. Should be used with InactiveCaptionText foreground color.

InactiveCaptionText

Color of text in an inactive caption. Should be used with InactiveCaption background color.

InfoBackground

Background color for tooltip controls. Should be used with InfoText foreground color.

InfoText

Text color for tooltip controls. Should be used with InfoBackground background color.

Menu

Menu background. Should be used with MenuText or -moz-MenuBarText foreground color.

MenuText

Text in menus. Should be used with Menu background color.

Scrollbar

Scroll bar gray area.

ThreeDDarkShadow

The color of the darker (generally outer) of the two borders away from the light source for 3-D elements that appear 3-D due to two
concentric layers of surrounding border.

ThreeDFace

The face background color for 3-D elements that appear 3-D due to two concentric layers of surrounding border. Should be used with ButtonText foreground color.

ThreeDHighlight

The color of the lighter (generally outer) of the two borders facing the light source for 3-D elements that appear 3-D due to two
concentric layers of surrounding border.

ThreeDLightShadow

The color of the darker (generally inner) of the two borders facing the light source for 3-D elements that appear 3-D due to two
concentric layers of surrounding border.

ThreeDShadow

The color of the lighter (generally inner) of the two borders away from the light source for 3-D elements that appear 3-D due to two
concentric layers of surrounding border.

Window

Window background. Should be used with WindowText foreground color.

WindowFrame

Window frame.

WindowText

Text in windows. Should be used with Window background color.

Mozilla System Color Extensions

-moz-ButtonDefault

The border color that goes around buttons that represent the default action for a dialog box.

-moz-ButtonHoverFace

The background color of a button that the mouse pointer is over (which would be ThreeDFace or ButtonFace when the mouse pointer is not over it). Should be used with the -moz-ButtonHoverText foreground color.

-moz-ButtonHoverText

The text color of a button that the mouse pointer is over (which would be ButtonText when the mouse pointer is not over it). Should be used with the -moz-ButtonHoverFace background color.

-moz-CellHighlight

Background color for selected item in a tree widget. Should be used with -moz-CellHighlightText foreground color. See also -moz-html-CellHighlight.

-moz-CellHighlightText

Text color for a selected item in a tree. Should be used with -moz-CellHighlight background color. See also -moz-html-CellHighlightText.

-moz-Combobox

{{ Gecko_minversion_inline("1.9.2") }} Background color for comboboxes. Should be used with -moz-ComboboxText foreground color. In versions prior to 1.9.2, use -moz-Field instead.

-moz-ComboboxText

{{ Gecko_minversion_inline("1.9.2") }} Background Text color for comboboxes. Should be used with -moz-ComboboxText foreground color. In versions prior to 1.9.2, use -moz-FieldText instead.

-moz-Dialog

Background color for dialog boxes. Should be used with -moz-DialogText foreground color.

-moz-DialogText

Text color for dialog boxes. Should be used with -moz-Dialog background color.

-moz-dragtargetzone

-moz-EvenTreeRow

{{ gecko_minversion_inline(1.9) }} Background color for even-numbered rows in a tree. Should be used with -moz-FieldText foreground color. In Gecko versions prior to 1.9, use -moz-Field. See also -moz-OddTreeRow.

-moz-Field

textfield background color. Should be used with -moz-FieldText foreground color.

-moz-FieldText

textfield foreground color. Should be used with -moz-Field, -moz-EvenTreeRow, or -moz-OddTreeRow background colors.

-moz-html-CellHighlight

{{ gecko_minversion_inline(1.9) }} Background color for highlighted item in HTML select. Should be used with -moz-html-CellHighlightText foreground color. Prior to Gecko 1.9, use -moz-CellHighlight.

-moz-html-CellHighlightText

{{ gecko_minversion_inline(1.9) }} Background color for highlighted item in HTML select. Should be used with -moz-html-CellHighlight background color. Prior to Gecko 1.9, use -moz-CellHighlightText.

-moz-mac-accentdarkestshadow

-moz-mac-accentdarkshadow

-moz-mac-accentface

-moz-mac-accentlightesthighlight

-moz-mac-accentlightshadow

-moz-mac-accentregularhighlight

-moz-mac-accentregularshadow

-moz-mac-chrome-active

{{ Gecko_minversion_inline("1.9.1") }}

-moz-mac-chrome-inactive

{{ Gecko_minversion_inline("1.9.1") }}

-moz-mac-focusring

-moz-mac-menuselect

-moz-mac-menushadow

-moz-mac-menutextselect

-moz-MenuHover

Background color for hovered menu item. Often similar to Highlight. Should be used with -moz-MenuHoverText or -moz-MenuBarHoverText foreground color.

-moz-MenuHoverText

Foreground color for hovered menu item. Often similar to HighlightText. Should be used with -moz-MenuHover background color.

-moz-MenuBarText

{{ Gecko_minversion_inline("1.9.2") }} Foreground color for text in menu bars. Often similar to MenuText. Should be used on top of Menu background.

-moz-MenuBarHoverText

Foreground color for hovered text in menu bars. Often similar to -moz-MenuHoverText. Should be used on top of -moz-MenuHover background.

{{ gecko_minversion_inline(1.9) }} Background color for odd-numbered rows in a tree. Should be used with -moz-FieldText foreground color. In Gecko versions prior to 1.9, use -moz-Field. See also -moz-EvenTreeRow.

-moz-win-communicationstext

{{ gecko_minversion_inline(1.9) }} Should be used for text in objects with appearance:-moz-win-communications-toolbox.

-moz-win-mediatext

{{ gecko_minversion_inline(1.9) }} Should be used for text in objects with appearance:-moz-win-media-toolbox.

Mozilla Color Preference Extensions

-moz-activehyperlinktext

User's preference for text color of active links. Should be used against default document background.